|Narrative of Mount St. Helens
"The May 18th eruption, viewed from the east in late morning. The eruptive cloud generated lightning which in turn started forest fires. Other fires were ignited by the initial blasts and later pyroclastic flows. Ash can be seen falling out of the cloud. Nearly 550 million tons of ash fell over a 22,000 square mile area on May 18th." (The Eruption, NGDC, p. 4) Photo: Courtesy of NGDC/NOAA.
"Mount St. Helens viewed from the north on June 4, 1980. The huge U-shaped basin formed by the landslide and the initial blast was nearly two miles long and one mile wide. The mountain was lowered 1,300 feet. Ash covered slopes and extensive mud flows are visible in the photograph. Mud flows dumped more than 75 million cubic yards of sediment into rivers, valleys, and reservoirs. Several pyroclastic flows left about 0.05 cubic mile of deposits in this area. About 230 square miles were devastated by the eruption." (The Eruption, NGDC, p.4) Photo: Courtesy of NGDC/NOAA.
All those within 5 to 10 miles of the volcano on the north side, scientist and layman alike, were doomed. Some took a few quick pictures. Then, realizing their situation, most ran or tried to drive away from the approaching cloud of dust and steam. The ash-laden cloud engulfed the area with a force sufficient to strip huge trees bare and uproot or break them off at ground level. The temperature within the cloud reached 500F and was sufficient to cause serious burns and start fires. The rock avalanche roared over Spirit Lake and the valley of the North Fork Toutle River, burying them under layers of rock up to several hundred feet thick. Photo: Courtesy of NGDC/NOAA.
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